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In verification using UVM, most of the people create sequences from sequence item and start the same sequence from the testcase. In this blog, we will see a different method to drive transactions without creating any sequence. UVM provides “uvm_random_stimulus” class which generates random transactions and put it on to “blocking_put_port”. So by using this port, we can get the random transaction and drive them on to the interface. “uvm_random_stimulus” class contains “generate_stimulus” method whose arguments are the transaction class and number of transaction to be generated. User can override this method to have his own implementation. It also contains “stop_stimulus_generation” function which stops generation of stimulus.

As we know, the integration of any VIP in the testbench is not completed until a sequence is driven from the driver and monitor samples interface properly. When we integrate any VIP, it may consume time in creating sequences and testcase which could be done later. Here if any error is generated, then user has to find whether there is any problem with component integration or it is related to the sequence or testcase. As this random stimulus generator method doesn’t include any sequences, one can easily stabilize the integration of VIP in the testbench. Error can be generated only because of integration problem (Note that, simulation time error will be printed for erroneous transactions. So constraints should be proper.). So, this method of transaction generation is very useful for the AE(application engineer) and also for a new user of the VIP.

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